1. The Field of the Invention
The present invention relates generally to a light-weight concrete panel or wall which appears as another building material, such as stone work, brick, wood or the like. More particularly, the present invention relates to a panel or wall having a thin concrete face layer with a molded contour or otherwise shaped to appear as stone work or the like, a reinforcing elastomer layer, and an inner foam layer.
2. The Background Art
Traditional walls have been constructed from individual stones, rocks, blocks, or bricks assembled together into the shape of a wall and held together with mortar. One problem with traditional walls of this type is they are typically expensive and time-consuming to construct. Another problem is their great weight.
Prior attempts have been made to simulate such stone work or brick walls using less expensive materials and less labor-intensive methods. One such attempt involves constructing a wall from concrete. The concrete may be molded to the shape of bricks or otherwise textured to appear as brick. For example, concrete sidewalks have been provided with textured surfaces by stamping a stone shape into the concrete before it hardens.
Another such example includes manually texturing the concrete before it cures. One problem with using concrete is that concrete tends to have a substantially smooth texture, unlike natural stone or brick. Another disadvantage with such concrete walls is that solid concrete is also extremely heavy.
Another attempt at providing such a textured or shaped surface includes veneering, in which actual or simulated stone or brick is adhered to a conventional concrete wall. One disadvantage with veneering is the expense, time and care involved in providing the veneer.
Another attempt simply involves making panels from plastic which has been molded. One disadvantage with such plastic panels is that they often do not provide a realistic appearance.
In addition, attempts have been made to reduce the weight of concrete, load bearing building elements. Such attempts include the addition of fillers into concrete. Another technique involves bonding a plurality of laminations, including adhering a lightweight laminate to the concrete laminate. Such techniques typically involve a foam block onto which a concrete mixture is applied or onto which a concrete laminate is adhered. One disadvantage with these techniques is that the foam block must be pre-shaped. Another disadvantage is that the building elements have thick concrete layers, and thus are heavy.
It has been recognized that it would be advantageous to develop a wall or panel which has the appearance of natural stone work, rock, brick, wood, or the like, which is lightweight and durable. The invention provides a wall or panel with a thin concrete layer to reduce the weight of the wall or panel. The concrete layer has interior and exterior surfaces, and a cross-sectional contour. The contour projects outwardly to form macro projections in the exterior surface, and macro indentations in the interior surface. The contour also projects inwardly to form macro indentations in the exterior surface, and macro projections in the interior surface. The contour, or projections and indentations, may form natural objects, such as stone work, brick, wood, and the like. In a more detailed aspect of the invention, the concrete layer has a substantially constant thickness at the projections and indentations. In another more detailed aspect of the invention, the concrete layer is less than approximately 0.5 inches thick to reduce weight.
A foam layer is coupled to the interior surface of the concrete layer, and has protrusions mating with the indentations in the interior surface of the concrete layer. The foam layer provides reinforcement to the thin concrete layer and reduces the weight of the wall or panel. The foam layer may have fiber reinforcement.
In accordance with one aspect of the present invention, the wall or panel may have a thin elastomer layer affixed to the concrete layer to reinforce the concrete layer, and to provide tensile strength and impact resistance. In a more detailed aspect of the invention, the reinforcement layer may include an elastomer layer, such as a urethane layer. Alternatively, the reinforcement layer may include a high density foam, and the foam layer may include a low density foam. The reinforcement layer may include fiber reinforcement.
In accordance with another aspect of the present invention, the wall or panel may have a rigid backing layer spaced-apart from the elastomer layer, with the foam layer disposed between, and affixed to, the elastomer layer and backing layer to further reinforce the concrete layer and making the wall or panel light-weight.
The rigid backing layer may be a second concrete layer spaced-apart from and opposite the first concrete layer. The second concrete layer may have a similar cross-sectional contour.
The wall or panel may be configured to be free-standing fencing structures. Alternatively, the wall or panel may be configured as a facade to be affixed to an exterior wall of a building.
A method for making the wall or panel includes providing a mold having an inner mold surface with macro indentations and macro protrusions. A wet mixture of concrete material is applied to the inner mold surface of the mold to form a concrete layer with a cross-sectional contour corresponding to the indentations and protrusions of the inner mold surface. Preferably, the concrete material is sprayed onto the inner mold surface. Preferably, the wet mixture of concrete material is applied in a substantially constant thickness at the projections and indentations. The concrete material is cured until dry.
Foam is introduced into the mold to form a foam layer secured to the cement layer with the foam having protrusions mating with the concrete layer. The mold provides support to the concrete layer as the foam expands. The secured concrete and foam layers are removed from the mold.
In accordance with one aspect of the method of the present invention, the layer of reinforcement material is applied to the concrete layer prior to introducing the foam to form a reinforcement layer. Preferably, the reinforcement layer is sprayed onto the cured concrete layer.
In accordance with another aspect of the method of the present invention, the rigid backing layer is spaced-apart from the mold surface prior to introducing the foam into the mold. Alternatively, the rigid backing layer may be applied to the foam layer.
In accordance with another aspect of the method of the present invention, the mold may be disposed in a vertical orientation, either throughout the process, or just before the foam is introduced into the mold. Thus, the wall or panel is vertically oriented to facilitate handling and conserve space.
Additional features and advantages of the invention will be set forth in the detailed description which follows, taken in conjunction with the accompanying drawing, which together illustrate by way of example, the features of the invention.